UNIVERSITY    OF   CALIFORNIA 

COLLEGE    OF    AGRICULTURE 
AGRICULTURAL   EXPERIMENT  STATION 

CIRCULAR  No.  220 
July,  1920 

UNFERMENTED   FRUIT  JUICES 

By  W.  V.  CRUESS 


During  recent  years  the  production  of  fruit  juices  has  very 
greatly  increased.  Several  factors  have  been  responsible  for  this  rapid 
development,  the  most  important  being  improvements  in  the  quality  of 
the  finished  products  and  effective  advertising. 

Because  of  the  increased  sale  for  these  products  there  has  arisen  an 
insistent  demand  for  information  upon  methods  of  manufacture.  It 
has  therefore  seemed  desirable  to  publish  the  available  information 
from  all  sources  (including  that  derived  from  our  own  investigations). 

GENERAL  PRINCIPLES 

Any  fruit  juice  is  most  attractive  when  it  is  first  pressed  from  the 
fresh  fruit ;  any  treatment  that  may  be  given  it  thereafter  injures  its 
delicate  flavor  and  aroma  more  or  less,  and  our  most  important  problem 
is  that  of  retaining  in  the  finished  product  as  much  as  possible  of 
the  pleasing  qualities  of  the  fresh  juice.  "We  may  improve  its  appear- 
ance by  making  it  clearer,  but  cannot  improve  upon  the  natural  flavor. 

1.  Preservation. — Fresh  fruit  juices  soon  spoil  completely  through 
fermentation  or  molding,  if  nothing  is  done  to  destroy  or  prevent  the 
growth  of  yeasts  and  molds.  These  are  easily  killed  by  temperatures 
between  160°  F.  and  180°  F.,  and  if  the  juice  is  hermetically  sealed 
before  sterilization  by  heat  it  will  not  spoil  so  long  as  the  container 
remains  sealed  against  the  entrance  of  living  yeast  or  mold  cells. 
Sterilizing  fruit  juices  at  temperatures  below  212°  F.  is  commonly 
termed  pasteurization  and  is  the  most  generally  used  process  of 
preservation.  It  must  be  carried  out  in  such  a  way  that  the  minimum 
injury  compatible  with  complete  sterilization  of  the  juice  shall  result. 
Too  high  a  temperature  of  pasteurizing  or  too  long  a  period  of  heating 
injures  the  fresh  fruit  flavor  and  will  impart  a  cooked  taste. 

Juices  held  in  cold  storage  at  32°  F.  or  above  will  in  time  (six 
months  or  less)   spoil;  but  if  maintained  in  the  frozen  condition  at 


Z  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

temperatures  below  32°  F.  (freezing)  will  keep  indefinitely.  The 
flavor  is  only  slightly  impaired  by  such  treatment.  This  method  of 
preservation  remains  to  be  tested  commercially,  but  appears  to  have 
great  possibilities. 

Chemical  preservatives  were  at  one  time  used  freely  to  preserve 
fruit  juices  but  are  now  less  popular.  Sodium  benzoate  is  the  most 
commonly  used  of  these  preservatives  and  is  allowed  by  law  if  declared 
on  the  label.  Sulfurous  acid  is  used  in  special  cases  to  preserve  grape 
juice  for  short  periods  but  not  for  permanent  preservation. 

If  sterilized  bottles  and  corks  are  used,  if  the  juice  is  filtered  per- 
fectly clear,  and  thus  practically  freed  of  molds  and  yeasts,  it  is 
possible,  when  great  care  and  skill  are  used,  to  preserve  juices  in 
bottles  with  heavy  pressures  of  carbon  dioxide  without  use  of  heat  or 
chemical  preservatives.  Juices  so  preserved  are  superior  in  flavor  to 
pasteurized  juices,  but  the  method  has  not  been  entirely  satisfactory 
in  practice  because  of  the  difficulty  in  avoiding  contamination  of  the 
juice  with  molds  and  yeasts.  This  process  was  patented  by  Mr.  W. 
Ruef  over  twenty  years  ago  and  his  process  is  therefore  now  open  to 
the  use  of  the  public. 

2.  Clearing  the  Juiee. — In  addition  to  preserving  the  juice  against 
fermentation  and  molding,  it  is  desirable  to  improve  the  appearance 
by  making  it  as  clear  as  possible.  Filtration  is  the  most  common 
method,  by  centrifugal  force  and  clarification  by  finings  (clarifying 
materials)  are  also  used.  The  latter  process  consists  in  adding  to  the 
juice  some  substance  such  as  white  of  egg  or  casein  which  coagulates 
and  settles  to  the  bottom  of  the  container,  carrying  down  the  particles 
of  pulp  and  other  solids  responsible  for  the  cloudiness  of  the  juice. 

3.  Cleanliness. — The  presence  of  a  small  amount  of  moldy  or  soured 
fruit  will  spoil  the  flavor  of  a  large  volume  of  the  product.  Only 
sound,  clean  fruit  should  be  used  and  all  fruit  should  be  carefully 
sorted.  Only  clean  press  cloths,  pumps,  sterilizers,  filters,  and  con- 
tainers can  be  employed  without  injury  to  quality.  Cleaning  and 
sterilizing  such  equipment  with  hot  water  and  steam  is  desirable. 
Press  cloths  and  other  equipment  should  be  kept  dry  when  not  in  use. 

EQUIPMENT 

Most  of  the  equipment  used  in  fruit  juice  manufacture  has  been 
developed  in  other  industries,  notably  in  wine  making,  brewing,  and 
vinegar  making.  The  most  common  forms  of  such  equipment  will  be 
described  briefly  and  illustrated.  More  complete  descriptions  may  be 
had  from  dealers  and  manufacturers. 


Circular  220  unfermented  fruit  juices  3 

1.  Sorting  Equipment. — Broad,  heavy  woven  endless  cotton  belts 
which  carry  the  fruit  to  be  sorted  slowly  past  the  sorters  are  often  used 
in  canneries  and  evaporators  for  sorting  purposes  and  may  be  used  to 
advantage,  especially  with  apples,  in  sorting  fruit  for  juice  manu- 
facture. Belts  made  of  metal  cloth  similar  to  ordinary  metal  door 
matting  are  very  satisfactory  because  they  may  be  easily  washed  and 
may  be  fitted  with  sprays  at  one  end  for  washing  the  sorted  fruit. 


Fig.  1.    Fruit  or  vegetable  washer;  suitable  for  washing  apples  before  crushing. 
(Courtesy  of  Berger  and  Carter  Company,  San  Francisco) 

2.  Washing  Equipment. — Fruit  often  arrives  at  the  factory  very 
dusty  or  soiled  from  contact  with  spoiled  fruit.  It  will  generally 
improve  the  quality  of  the  product  in  all  cases  to  wash  the  fruit  before 
crushing.  The  most  effective  washing  device  for  fruits  that  will  with- 
stand rough  treatment  is  the  rotary  tomato  washer ;  others  may  be 
washed  in  the  machine  shown  in  figure  1  or  under  sprays  of  water. 

3.  Crushers. — The  most  satisfactory  type  of  crusher  for  general  use 
is  that  commonly  used  for  apples  under  the  name  of  "apple  grater." 
It  consists  of  a  cylinder  on  the  surface  of  which  are  fixed  short  knives 
and  in  some  cases  a  set  of  concaves  or  upright  knives  against  which 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

the  cylinder  revolves,  or  in  other  styles  a  corrugated  plate,  the  fruit 
being  grated  or  crushed  between  the  plate  and  cylinder.  The  upright 
knives  or  the  corrugated  plate  are  fixed  to  strong  springs  in  order  that 
the  crusher  will  have  flexibility  and  not  be  broken  by  pieces  of  wood 
or  stone  which  may  accidently  fall  into  the  crusher. 


Fig.  2.  Balling  hydrometer  and  cylinder  for  testing  sugar  content  of  juice. 

For  grapes  the  best  crusher  is  the  one  formerly  in  common  use  for 
crushing  grapes  for  wine  making.  It  consists  of  two  corrugated  or 
fluted  metal  rollers  which  revolve  closely  together  and  toward  each 
other,  carrying  downward  between  them  and  crushing  the  grapes  fed 
into  a  hopper  above.  Connected  with  the  crusher  is  a  stemmer  con- 
sisting of  a  horizontal  metal  cylinder  with  perforated  bottom,  through 
which  the  grapes  are  forced  by  revolving  paddles.  The  stems  cannot 
pass  through  these  openings  and  are  thrown  out  at  the  end  of  the 
crusher.    Grapes  for  red  juice  making  should  be  stemmed. 


Circular  220 


UNFERMENTED    FRUIT    JUICES 


For  farm  use  small  hand  power  crushers,  usually  with  a  press 
mounted  on  the  same  frame,  are  available.  These  are  designed  either 
for  grapes  or  apples,  but  the  apple  crusher  style  will  find  the  greatest 
application,  being  suited  to  both  apples  and  soft  fruits. 

4.  Presses. — The  press  known  as  the  "rack  and  cloth"  press  will 
give  a  higher  yield  of  juice  than  will  the  basket  press.     In  the  rack 


Fig.  3.    Fruit  crusher  and  press.    Used  in  Fruit  Products  Laboratory 
of  University  of  California. 


and  cloth  press  the  crushed  fruit  is  built  up  in  layers  in  heavy  press 
cloths  between  racks  made  of  wooden  slats.  Pressure  is  ordinarily 
applied  by  means  of  an  hydraulic  pump,  although  cog  gears  are  often 
used.    It  is  usually  attached  to  the  same  frame  as  the  crusher. 

In  basket  presses  the  cloths  and  racks  are  not  used.  The  crushed 
fruit  is  held  in  a  strongly  reinforced  wooden  basket  of  cylindrical 
shape,  which  rests  on  the  press  floor.  The  basket  is  movable.  Pres- 
sure is  applied  by  a  lever  and  screw  in  small  outfits  and  by  hydraulic 
pressure  in  the  larger  presses. 


(j  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

A  very  satisfactory  home  made  press  can  be  made  of  farm  equip- 
ment arranged  as  shown  in  figure  18.  It  may  be  used  either  with 
racks  and  cloths  or  with  a  basket. 

5.  Pasteurizers  for  Juice  in  Bulk. — Most  juices  before  filtering 
should  be  heated  to  coagulate  proteins  and  gums  which  would  other- 
wise precipitate  in  the  bottle  and  cause  cloudiness.  Grape  juice  is 
usually  sterilized  and  stored  several  months  to  permit  separation  of 
cream  of  tartar  before  bottling.  This  sterilization  is  accomplished 
upon  a  large  scale  by  use  of  some  one  of  the  pasteurizers  described 
below. 


Fig.  4.     Large  size  apple  grater  and  press. 
(Courtesy  of  Hydraulic  Press  Manufacturing  Company) 

A  very  common  and  effective  sterilizer  consists  of  a  block  tin  or 
aluminum  pipe  surrounded  by  a  steam  jacket.  The  juice  flows  through 
the  inner  pipe  and  steam  admitted  to  the  jacket  heats  the  juice  to  any 
desired  temperature.  A  thermometer  at  the  juice  outlet  is  necessary 
for  control  of  temperature.  The  hot  juice  may  be  delivered  by  means 
of  a  hose  to  the  final  containers  in  place  on  shelves  or  racks. 

An  objection  sometimes  made  to  this  pasteurizer  is  that  the  juice 
in  contact  with  the  walls  of  the  pasteurizer  may  be  overheated  and 
impart  a  cooked  taste  to  the  juice.  This  is  overcome  if  the  juice  pipe 
is  surrounded  by  hot  water  instead  of  steam  as  indicated  in  figure  12. 
This  type  has  been  used  very  successfully  in  our  experiments. 


Circular  220 


UNFERMENTED    FRUIT    JUICES 


Ordinary  large  steam  jacketed  aluminum  walled  jelly  kettles  are 
very  commonly  used  in  the  eastern  grape  growing  districts  of  the 
United  States.    See  figure  11. 

Another  common  form  of  discontinuous  pasteurizer  consists  of  a 
tank  or  barrel  in  which  is  placed  an  aluminum  steam  coil  or  a  tin- 
coated  copper  coil.  The  tank  is  filled  with  juice  and  steam  admitted 
to  the  coil  heats  the  juice  to  the  pasteurizing  temperature.  This  type 
is  objectionable  because  of  excessive  exposure  to  the  air  and  danger  of 
scorching  of  the  juice  in  immediate  contact  with  the  coils. 


Fig.  5.    Large  size  grape  crusher  and  stemmer. 
(Courtesy  of  E.  T.  Meakin) 

6.  Filters. — Some  fruit  juices  should  be  made  as  clear  as  possible 
before  bottling.     This  usually  involves  filtration. 

The  simplest  filter  is  the  bag  filter,  which  consists  of  a  conical 
heavy  duck  or  felt  bag  which  is  used  in  the  same  manner  as  an  ordinary 
jelly  bag.  The  rate  and  effectiveness  of  filtration  are  increased  by 
the  addition  of  infusorial  earth  to  the  juice  before  filtration,  although 
the  flavor  of  the  juice  may  be  affected.  Bag  filters  commonly  hold 
ten  gallons  of  juice  at  each  filling.  They  are  very  satisfactory  for 
small  scale  operations. 


8 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


For  larger  scale  manufacture  of  fruit  juices  some  form  of  wood  or 
cotton  pulp  filter  is  generally  used.  Wood  pulp  filters  vary  greatly  in 
appearance  and  design.  Figure  13  illustrates  a  very  effective  type.  It 
consists  of  several  thick  disks  of  wood  pulp  in  a  tin-lined  copper 
cylinder.  The  discs  of  pulp  are  separated  by  metal  screens  and  the 
juice  is  admitted  to  the  cylinder  in  such  a  way  that  each  layer  of  pulp 
acts  as  an  independent  filter,  thus  giving  a  very  large  aggregate  filter- 


Fig.  6.     Basket  type  of  hydraulic  press.     Suitable  for  grapes. 
(Courtesy  of  E.  T.  Meakin) 

ing  surface.  The  pulp  is  washed  after  use  by  stirring  in  water  by 
means  of  a  mechanical  agitator.  It  is  then  pressed  into  discs  and  used 
over  again  in  the  filter.  A  certain  amount  of  cotton  fiber  is  usually 
mixed  with  the  wood  pulp  to  act  as  a  binder,  or  cotton  fiber  is  often 
used  to  replace  wood  pulp  entirely. 

A  form  of  pulp  filter  known  as  the  "Dutch  wood  pulp  filter"  con- 
sists of  a  screen  and  enclosing  cylinder.  Pulp  is  packed  upon  the 
screen  to  act  as  a  filter. 


Circular  220 


UNFERMENTED    FRUIT    JUICES 


9 


The  Seitz  filter  consists  of  a  very  fine  tin  or  silver  screen,  usually 
conical  in  shape,  enclosed  in  a  cylinder.  The  first  juice  to  be  passed 
through  the  filter  is  mixed  with  asbestos  fiber  of  a  special  grade  manu- 
factured for  this  filter,  which  forms  a  filtering  surface  on  the  screen. 

Filter  presses  are  used  in  many  industries  for  filtering  large 
volumes  of  various  liquids  and  have  also  been  used  successfully  for 
fruit  juices.  Filtration  is  accomplished  by  forcing  the  liquid  under 
heavy  pressure  through  cloth  or  canvas  sheets  held  between  metal  or 
wooden  plates.     "  Filter- Cel,"  a  special  form  of  infusorial  earth,  is 


Fig.  7.     Hand  power  fruit  crusher. 
(Courtesy  of  Hydraulic  Press  Manufacturing  Company) 


often  added  to  the  liquid  to  be  filtered  to  aid  filtration.  Metal  parts 
in  contact  with  juices  should  be  heavily  tinned  or  silver  plated. 

7.  Containers — Grape  juice  is  usually  stored  several  months  at  a  low 
temperature  to  allow  the  excess  of  cream  of  tartar  to  separate  and  to 
aid  clarification.  Some  factories  use  50-gallon  barrels  for  storage,  but 
20-gallon  or  smaller  glass  carboys  (demijohns)  are  better  because  glass 
does  not  injure  the  flavor  of  the  juice. 

Glass  bottles  are  the  usual  final  packages  in  which  the  juices  are 
sold.  Two  types  are  in  use :  those  closed  with  an  ordinary  crown  or 
soda  water  bottle  cap  and  those  upon  which  the  Goldy  caps  are  used. 
The  Goldy  caps  may  be  removed  without  the  use  of  soda  bottle  opener. 


10 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Both  styles  of  caps  are  applied  by  special  machines,  which  fasten  the 
caps  to  the  bottles  by  pressure.     See  figures  16  and  17. 

Cans  may  be  used  for  white  juices,  but  the  color  of  red  juices  often 
changes  to  blue  or  purple  in  tin  or  lacquered  tin  containers. 

8.  Bottle  Pasteurizers. — Large  glass  carboys  used  for  storage  of 
juices  are  sterilized  by  means  of  live  steam  in  an  enclosed  box  into 
which  the  carboys  may  be  run  on  a  truck.  The  empty  carboys  are 
sterilized  in  this  way  just  before  they  are  to  be  filled  with  hot  juice. 

Filled  bottles  or  cans  of  juice  are  sterilized  by  heating  them  in 
water  to  the  desired  temperature. 


Fig.  8.    Small  hand  jiower  basket  press  for  all  varieties  of  fruit. 


The  pasteurizer  may  consist  of  a  shallow  metal  or  wooden  vat  with 
perforated  false  bottom  to  hold  bottles  or  cans  and  a  perforated  steam 
coil  beneath  the  false  bottom. 

9.  Steam  Supply. — A  steam  plant  will  be  necessary  except  for  the 
very  smallest  factories.  To  operate  a  pasteurizer  capable  of  sterilizing 
500  gallons  of  juice  per  hour  a  25  H.P.  boiler  should  be  available; 
other  sizes  in  proportion  to  output.  Steam  is  also  necessary  for 
sterilizing  empty  barrels,  carboys,  pipe  lines,  press  cloths,  etc.,  that 
come  in  contact  with  the  juice;  but  if  the  boiler  is  large  enough  to 
operate  the  pasteurizer,  it  will  also  furnish  enough  steam  for  these 
miscellaneous  purposes.  Steam  and  an  abundance  of  water  are  very 
desirable. 


Circular  220 


UNFERMENTED    FRUIT    JUICES 


11 


10.  Bottle  Filling  Machines. — In  the  production  of  bottled  juices 
in  quantity  some  form  of  automatic  bottle  filler  will  be  needed.  Those 
formerly  used  in  breweries  answer  the  purpose  very  well.  For  the 
small  factory  a  soft  half-inch  hose  and  a  small  hand  bottle  filling  device 
may  be  used. 

11.  Labeling  Machines. — Bottles  or  cans  may  be  labeled  by  special 
machines  much  more  rapidly  and  just  as  neatly  as  by  hand.  Such  a 
machine  is  practically  a  necessity  for  large  plants,  but  is  not  needed 
in  small  plants. 


Fig.  9.    Small  combination  crusher  and  press  suitable  for  household 
scale  production  of  fruit  juices. 

12.  Equipment  for  Home  Manufacture  of  Juices. — Small  combina- 
tion fruit  crushers  and  presses  for  use  in  the  kitchen  may  be  bought 
through  any  hardware  store.  (Figure  9,  name  of  manufacturer  on 
request.)  Grapes  and  berries  may  be  crushed  with  a  potato  masher 
or  the  hands  and  pressed  in  a  small  meat  press.  An  ordinary  jelly 
bag  made  of  muslin  or  flannel  will  serve  for  a  filter.  A  wash  boiler 
fitted  with  a  false  bottom  may  be  used  as  a  pasteurizer. 


GRAPE  JUICE  MANUFACTURE 

1.  Desirable  Qualities  of  Grape  Juice. — A  red  juice  is  commonly 
preferred,  and  the  more  intense  the  color  the  better.  High  acidity, 
that  is,  a  tart  flavor,  is  necessary  in  a  successful  product.     Clearness 


12  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

is  desirable  but  not  essential,  although  a  heavy  deposit  of  pulp  should 
never  accumulate  in  the  bottled  product.  Canned  juice  may  be  slightly 
cloudy. 

In  addition  to  these  qualities  the  juice  must  have  a  distinctive  and 
pleasing  flavor.  In  a  popular  juice  this  flavor  must  be  very  pro- 
nounced. However,  it  has  been  demonstrated  that  grape  juice  of  a 
fine  and  delicate  flavor  may  be  made  from  the  finer  varieties  of  wine 
grapes  grown  in  California  and  that  this  type  of  juice  is  preferred 
by  some  consumers. 

2.  Varieties  of  Grapes  for  Juice. — At  present  the  most  popular 
juices  are  those  made  from  the  Concord  and  other  closely  related 
eastern  (i.e.,  Labrusca)  varieties.  In  California  the  Pierce  Isabella 
could  be  used  as  a  substitute  for  the  Concord,  as  it  combines  in  a 
single  variety  high  color,  high  acid,  and  a  strong  "foxy"  flavor.  It 
may  be  grown  most  successfully  in  the  coast  counties. 

None  of  the  commonly  grown  Calif ornian  (European)  varieties 
possess  in  a  single  variety  all  of  the  desired  qualities.  The  Muscat 
has  a  strong  flavor  but  is  white  in  color  and  not  very  high  in  acid. 
When  blended  with  suitable  varieties  of  red  wine  grape  juices  a  very 
excellent  product,  which  compares  favorably  with  Concord  juice  in 
color,  acid,  and  flavor,  may  be  made.  It  is  believed  that  such  a  juice 
can  be  made  a  strong  competitor  of  eastern  juices.  The  better  varieties 
or  red  wine  grapes  such  as  St.  Macaire,  Barbera,  Valdepenas,  and 
Crabbe's  Black  Burgundy,  give  better  results  than  do  the  commoner 
varieties,  such  as  Petite  Sirah,  Zinfandel,  Alicante  Bouschet,  Carig- 
nane,  and  others,  but  these  latter  varieties  may  be  used  successfully 
to  blend  with  Muscat  juice. 

For  the  production  of  juices  of  delicate  flavor,  which  will  appeal 
to  connoisseurs  of  fine  wines,  varieties  such  as  Semillon,  Franken 
Riesling,  or  Colombar  should  be  blended  with  acid  varieties,  such  as 
Burger  or  "West's  White  Prolific.  There  should  be  a  demand  for  an 
appreciable  quantity  of  such  juices  at  high  prices  among  the  former 
users  of  fine  wines. 

3.  Gathering  the  Grapes. — The  composition  of  the  finished  juice 
is  governed  by  the  time  of  picking  the  grapes.  Eastern  varieties 
should  be  gathered  at  about  17  per  cent  to  18  per  cent  Balling  as 
indicated  by  the  Balling  "sugar"  tester  shown  in  figure  2.  This  per- 
centage of  sugar  is  easily  reached  in  California,  but  is  difficult  to 
obtain  in  eastern  grape  growing  regions. 

Muscat,  Semillon,  and  other  flavor  grapes  must  reach  the  stage  of 
maturity  at  which  their  flavor  is  well  developed.    This  is  22  per  cent 


Circular  220  unfermented  fruit  juices  13 

to  23  •  per  cent  Balling.  The  acid  grapes  to  blend  with  the  flavor 
grapes  should  have  a  good  color  but  still  be  very  sour ;  that  is,  about 
17  per  cent  Balling.  With  Zinfandel  grapes,  in  order  to  obtain  both 
acid  and  color,  it  will  be  necessary  to  gather  the  first  crop  at  20  per 
cent  to  22  per  cent  Balling  for  color  and  at  the  same  time  enough  of 
the  second  crop  to  impart  a  very  tart  flavor.  Ordinarily  the  color  and 
acid  varieties  will  have  to  be  gathered  several  weeks  before  the  flavor 
varieties  have  ripened  sufficiently. 

A  test  of  the  acidity  of  the  grapes  is  important.  The  finished  juice 
should  contain  from  .9  to  1.1  per  cent  acid  expressed  as  tartaric  acid. 
This  test  is  simple  and  can  be  made  with  equipment  which  may  be 
obtained  from  any  chemical  supply  house.  Names  of  these  companies 
will  be  furnished  upon  request. 


Fig.  10.    Steam  heated  continuous  pasteurizer  for  fruit  juices. 

A,  juice  valve;  B,  steam  valve;  C,  juice  inlet;  D,  to  sewer;  E,  to  steam  trap; 

F,  steam  inlet;  G,  thermometer;  E,  juice  outlet. 

(Courtesy  of  Hydraulic  Press  Manufacturing  Company) 

To  make  the  test  measure  10  c.c.  of  the  juice  by  means  of  a  10  c.c. 
pipette  into  a  tumbler.  Add  water  to  fill  the  tumber  one-quarter  full. 
Add  a  few  drops  of  phenolphthalein  indicator  solution.  Fill  the 
burette  with  tenth  normal  sodium  hydroxide  solution  and  read-  the 
level  of  the  liquid  in  the  burette.  Add  the  tenth  normal  sodium 
hydroxide  solution  slowly  to  the  juice  in  the  tumbler  until  one  drop 
finally  turns  the  liquid  in  the  tumbler  permanently  pink.  Read  the 
level  of  the  liquid  in  the  burette  again.  The  difference  between  the 
first  and  second  readings  represents  the  amount  of  solution  needed  to 
neutralize  the  acid  of  the  juice.     This  figure  multiplied  by  .075  will 


14  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

give  the  acidity  of  the  juice  in  per  cent.     Example :  1st  reading,  4.0 ; 
2d  reading,  15.5.      Difference,  11.5.      Acidity  =  11.5  X  .075  =  .86%. 
The  grapes  should  be  crushed  as  soon  after  picking  as  possible  to 
forestall  molding  or  souring.    Only  clean  lug  boxes  should  be  used. 

4.  Crushing  and  Stemming. — The  grapes  must  be  thoroughly 
crushed.  White  grapes  should  not  be  stemmed  because  the  stems  aid 
in  pressing.  Red  wine  grapes  should  be  stemmed  for  the  reason  that 
heating  the  juice  later  to  extract  the  color  will  leach  from  the  stems  an 
astringent  principle  of  disagreeable  flavor. 

5.  Pressing. — White  grapes  must  be  as  completely  pressed  as  pos- 
sible without  heating.  The  color  of  grapes  used  for  red  juice  is  held 
in  the  skins  and  this  must  be  extracted  by  heat.  Therefore,  such 
grapes  are  not  finally  pressed  until  the  juice  has  been  heated  upon 
the  skins. 

6.  Extraction  of  Color. — There  are  two  methods  in  use  for  extrac- 
tion of  color.  The  most  commonly  used  process  consists  of  heating 
the  mixed  skins  and  juice  in  a  large  double  jacketed  steam-heated 
aluminum  kettle  to  160°  F.  for  a  few  minutes.  The  grapes  are  then 
pressed  hot  at  once. 

The  other  method  consists  in  first  lightly  pressing  the  crushed 
stemmed  grapes  to  obtain  one-half  or  two-thirds  of  the  juice.  The 
pomace  (pressed  skins  and  seeds)  is  thrown  into  a  clean  wooden  vat. 
The  juice  is  heated  in  one  of  the  bulk  pasteurizers  previously  described, 
to  about  140°  F.,  is  then  mixed  with  the  pomace  and  allowed  to  stand 
until  sufficient  color  is  extracted.  This  will  be  four  to  eight  hours. 
The  skins  and  juice  should  be  frequently  stirred  to  hasten  color 
extraction.  The  grapes  may  then  be  pressed.  Heating  destroys  the 
slimy  character  of  the  crushed  grapes  and  thus  facilitates  pressing. 

The  second  method  described  above  for  color  extraction  has  given 
the  better  results  in  our  experiments  because  it  avoids  danger  of  over- 
heating the  skins  or  juice.  High  temperatures  (150°  F.  to  180°  F.) 
of  mixed  juice  and  skins  cause  the  juice  to  develop  a  harsh  flavor, 
probably  because  of  materials  extracted  from  the  seeds.  We  have 
found  that  temperatures  of  mixed  skins  and  juice  of  130°  F.  to  110°  F. 
give  the  best  flavor  and  at  the  same  time  permit  of  satisfactory 
extraction  of  color. 

7.  First  Pasteurizing. — The  juice  must  be  heated  to  coagulate 
proteins,  which  would  cause  the  juice  to  be  cloudy  if  bottled  direct 
from  the  press.  If  cream  of  tartar  crystallization  in  the  bottled 
product  is  to  be  prevented,  the  juice  must  be  stored  several  months  to 
permit  this  to  separate  before  final  bottling;  and  in  order  that  the  juice 


Circular  LJ20 


UNFERMENTEO    FRUIT    JUICES 


15 


will  not  ferment  during  this  storage  it  must  be  sterilized  in  or  into 
sealed  containers. 

In  some  grape  juice  factories  the  juice  is  heated  to  175°  F.  to 
190°  F.  in  aluminum  kettles  and  then  transferred  at  this  temperature 
to  glass  carboys  that  are  still  hot  from  having  been  sterilized  in  steam. 
Any  one  of  the  continuous  pasteurizers  previously  described  may  also 
be  used.  The  carboys  in  either  case  are  filled  to  overflowing  and  are 
then  sealed  with  corks  sterilized  in  scalding  hot  melted  paraffin.  The 
tops  of  the  carboys  and  corks  are  then  sealed  with  paraffin  or  wax. 


Fig.  11.    Battery  of  steam  jacketed  aluminum  kettles  used  for  fruit  juices 
and  jellies.     (Courtesy  of  Wearever  Aluminum  Company) 


In  California  25-  or  50-gallon  barrels  are  often  used  instead  of  glass 
containers.  The  barrels  must  be  sound  and  sweet.  New  barrels  should 
first  be  treated  with  hot  soda  ash  solution  and  several  days'  leaching 
with  hot  water  to  remove  the  oak  flavor.  Just  before  they  are  to  be 
filled,  the  barrels  are  thoroughly  steamed  and  the  hot  juice  is  filled  into 
them.  They  are  bunged  tightly  with  ordinary  shipping  bungs  and 
muslin.  Both  the  bungs  and  muslin  must  be  sterilized  several  minutes 
in  boiling  water  before  use.  After  filling  and  bunging,  the  barrels 
should  be  rolled  slightly  on  their  sides  to  permit  the  hot  juice  to 


16  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

sterilize  the  bungs.  The  barrels  should  be  thoroughly  painted  with 
melted  paraffin  or  shellac  to  render  the  wood  airtight.  Barrels  have 
been  proved  by  repeated  tests  to  be  very  much  inferior  to  glass  con- 
tainers for  storage  because  they  injure  the  flavor  of  the  juice  and 
permit  browning  of  the  color  through  oxidation.  Their  use  is  not 
recommended  if  large  glass  carboys  are  obtainable. 

8.  Storage. — Separation  of  cream  of  tartar  is  greatly  hastened  by 
low  temperatures.  Therefore  large  factories  use  refrigeration  during 
storage.  Where  refrigeration  is  not  available  the  same  results  are 
obtained  by  simply  storing  the  juice  through  the  winter  until  February 
or  March  in  a  room  which  reaches  outside  winter  temperatures.  Our 
tests  show  that  storage  until  February  15th  is  sufficient.  By  leaving 
the  doors  open  on  cold  nights  and  closed  during  the  day,  the  desired 
temperatures  will  be  readily  attained. 

The  containers  should  be  on  shelves  or  racks  well  above  the  floor 
in  order  that  the  juice  may  be  drawn  off  after  storage. 

9.  Drawing  Off  after  Storage. — The  settled  juice  after  storage  must 
be  drawn  off  the  sediment.  This  is  most  conveniently  done  by  syphon- 
ing. A  half-inch  soft  rubber  hose  attached  to  a  short  gooseneck  of 
three-eighths  inch  tinned  copper  or  brass  pipe  makes  a  convenient 
syphon.  The  gooseneck  rests  on  the  bottom  of  the  carboy  or  tank,  the 
inlet  being  slightly  above  the  level  of  the  sediment  in  the  container. 
Thus  the  juice  is  drawn  downward  into  the  syphon  and  the  sediment 
is  not  disturbed. 

The  juice  may  be  drawn  off  by  means  of  a  plain  hose  without  use 
of  gooseneck  if  care  is  used.  A  piece  of  half-inch  bent  glass  tubing 
about  three  feet  long  and  attached  to  a  hose  make  a  convenient  racking 
syphon. 

10.  Filtration. — Some  Eastern  grape  juice  manufacturers  merely 
strain  the  juice  from  the  storage  containers  through  cloth.  A  much 
clearer  product  may  be  obtained  by  filtration  by  means  of  one  of  the 
filters  previously  described.  If  the  racking  (drawing  off)  of  the  juice 
after  storage  has  been  well  done,  filtration  is  rapid. 

11.  Clarification. — Some  juices  do  not  settle  satisfactorily  in  stor- 
age and  are  difficult  to  filter.  These  may  be  made  clear  by  the  addition 
of  a  suitable  clarifying  agent,  followed  by  pasteurization  and  settling. 
The  clarifying  agent  may  be  added  to  the  juice  before  the  first  pasteur- 
ization, but  if  this  is  to  be  done  the  juice  should  be  permitted  to  settle 
ten  hours  if  red  and  twenty-four  hours  if  white,  after  pressing  and 
before  the  clarifying  material  is  added,  in  order  to  remove  coarse 
particles  of  pulp,  etc.    The  clarifying  agent  is  most  commonly  added, 


Circular  220  unfermented  fruit  juices  17 

however,  after  the  juice  has  remained  in  storage.  This  practice  makes 
it  necessary  to  clarify  only  those  lots  of  juice  which  have  failed  to 
settle  satisfactorily  during  storage.  The  clarifying  agents  used  in 
factories  and  also  found  most  suitable  in  our  experiments  are  egg 
albumen,  casein,  and  Spanish  clay. 

Dried  egg  albumen  may  be  purchased  in  granular  form.  It  is  first 
ground  and  then  dissolved  by  soaking  in  water  at  the  rate  of  three 
ounces  of  the  egg  albumen  per  gallon  of  water.  About  four  gallons 
of  this  solution  are  added  to  each  100  gallons  of  juice ;  although  the 
amount  needed  will  vary  with  the  juice.  The  two  are  mixed  thoroughly 
and  heated  to  175°  F.  to  180°  F.  in  most  factories,  and  the  juice  is  then 
transferred  hot  to  sterilized  barrels  or  carboys  and  sealed  to  permit 
settling.  If  successful,  the  juice  may  be  drawn  off  perfectly  clear. 
The  objection  to  egg  albumen  is  its  tendency  to  produce  a  deposit  in 
the  juice  after  clarification  and  bottling. 

Casein  is  less  likely  to  give  a  deposit  after  bottling  but  causes  con- 
siderable bleaching  of  the  color.  It  is  purchased  in  fine  granular  form. 
It  is  soluble  only  in  alkaline  solutions  such  as  dilute  spirits  of  ammonia 
or  soda  ash  or  soda  lye,  etc.  A  very  excellent  method  of  preparing 
the  solution  is  to  mix  with  each  three  ounces  of  casein  used  about  three 
fluid  ounces  of  strong  ammonia  water ;  allow  to  stand  about  one-half 
an  hour  and  then  add  two  quarts  of  water.  Boil  with  stirring  until 
practically  all  odor  of  ammonia  disappears.  Dilute  to  one  gallon  with 
water.  Use  two  to  three  gallons  of  this  solution  to  each  one  hundred 
gallons  of  juice.  The  treatment  thereafter  is  the  same  as  for  egg 
albumen,  although  casein  settles  more  rapidly  and  completely  than 
does  egg  albumen  and  the  juice  may  usually  be  drawn  from  the  sedi- 
ment and  filtered  for  bottling  within  twenty-four  to  forty-eight  hours 
after  clarification.  The  acid  of  the  juice  is  the  agent  which  causes 
the  casein  to  separate. 

Spanish  clay  is  a  brown  clay  high  in  organic  matter,  imported  from 
Spain.  It  is  at  present  difficult  to  obtain.  One  pound  of  the  clay  is 
mixed  with  one  gallon  of  water  and  the  mixture  agitated  in  a  barrel 
arranged  upon  a  shaft  so  that  it  may  be  rotated  end  for  end  for  several 
hours  by  means  of  a  pulley  and  belt;  a  fine-grained  thin  mud  free 
from  coarse  lumps  must  be  obtained.  Four  to  eight  gallons  of  this 
"solution"  is  used  per  hundred  gallons  of  juice.  It  may  be  used  in 
combination  with  casein  or  egg  albumen  solutions  to  advantage.  It 
settles  very  rapidly,  usually  in  less  than  twenty-four  hours ;  therefore 
it  is  not  necessary  to  pasteurize  juice  treated  with  Spanish  clay,  if 
the  juice  has  been  previously  heated  to  coagulate  the  proteins  of  the 


18  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

juice.  Spanish  clay  is,  however,  open  to  the  objection  that  it  may 
occasionally  cause  a  deposit  in  the  juice  after  bottling. 

Juices  that  are  clarified  as  noted  above  must  also  usually  be  filtered 
before  bottling  to  remove  floating  particles  of  the  clarifying  materials, 
but  filtration  will  be  much  more  rapid  and  the  filtered  juice  brighter 
than  is  the  case  where  clarifiers  are  not  used. 

Juice  from  eastern  varieties  of  grapes  cannot  be  successfully 
clarified  because  of  the  high  pectin  and  gum  content  of  such  grapes. 
Muscat  juice  is  also  difficult  to  clarify. 

In  most  cases  filtration  alone  will  accomplish  the  desired  results 
and  is  less  troublesome  than  clarification. 

12.  Bottling. — After  removal  of  cream  of  tartar  and  after  the  juice 
is  made  clear  as  described  above,  it  is  filled  into  bottles.  Quart  bottles 
must  be  filled  only  to  within  about  one  and  a  half  inches  of  the  top, 
this  space  being  necessary  for  expansion  of  the  juice  during  pasteur- 
izing. An  automatic  bottle  filling  machine  will  hasten  this  Avork.  The 
bottles  must  be  thoroughly  washed  before  use  and  should,  if  facilities 
permit,  be  sterilized  in  live  steam  a  short  time  before  filling,  but  must 
be  cool  at  time  of  filling. 

The  caps  used  in  sealing  the  bottles  should  be  placed  in  live  steam 
or  boiling  water  for  a  period  of  about  one  minute  just  before  use. 
This  will  destroy  mold  spores  on  and  in  the  cork  of  the  bottle  cap. 
Practically  all  spoiling  of  juice  in  bottles  by  mold  growth  is  caused 
by  the  resistant  mold  spores  to  be  found  on  all  such  non-sterilized  caps. 
The  cork  is  a  poor  conductor  of  heat  and  thus  protects  the  spores 
during  sterilization  of  the  juice;  hence  the  need  of  sterilizing  the 
corks  or  caps  before  use. 

13.  Pasteurizing  Bottled  Juice. — The  bottled  juice  must  be  steril- 
ized at  once  by  heat  to  prevent  spoiling.  A  temperature  of  165°  F. 
to  170°  F.  for  thirty  minutes  in  the  bottles  is  necessary  to  insure 
complete  sterilization  of  juice  which  is  not  carbonated.  The  bottles 
are  placed  in  a  horizontal  position  on  the  false  bottom  of  the  sterilizer 
in  order  that  the  juice  shall  be  in  contact  with  the  cap  and  thus  make 
certain  that  the  inner  cork  disc  of  the  cap  reaches  the  sterilizing 
temperature  of  the  juice.  If  the  bottle  is  in  an  upright  position  the 
air  space  in  the  top  of  the  bottle  acts  as  an  insulator  and  prevents  the 
cap  being  thoroughly  heated.  The  bottles  are  covered  with  water  and 
the  water  heated  by  steam  or  direct  heat  to  170°  F.  to  172°  F.  and 
kept  at  this  temperature  thirty  minutes.  Tests  have  shown  that  there 
will  be  about  2°  F.  difference  between  the  temperatures  of  the  bottled 
juice  and  the  surrounding  water. 


Circular  220 


UNFERMENTED    FRUIT    JUICES 


19 


The  water  is  then  drawn  from  the  pasteurizer  and  the  bottles 
placed  in  a  room  free  from  violent  drafts  of  cool  air;  or  may,  if 
desired,  be  allowed  to  cool  in  the  pasteurizer.  The  latter  practice 
avoids  the  necessity  of  handling  the  hot  bottles. 

14.  Storing  Bottled  Juice. — The  finished  juice  should  be  held  for 
at  least  four  weeks  at  a  warm  room  temperature  to  determine  whether 
it  will  remain  clear  and  free  from  mold. 

15.  Bottling  Juice  without  Removal  of  Cream  of  Tartar. — The 
juice  may  be  bottled  twenty-four  hours  after  crushing  of  the  grapes 
if  bottled  without  storage  to  remove  cream  of  tartar.     The  juice  may 


Fig.  12.  Continuous  water  heated  aluminum  coil  used  at  University  Farm 
for  pasteurizing  grape  juice  into  barrels.  At  left,  complete  pasteurizer.  At  right, 
coil.     The  juice  to  be  sterilized  flows  through  the  coil.     Designed  by  F.  T.  Bioletti. 


be  made  clear  by  processes  already  described ;  may  then  be  bottled  and 
pasteurized,  the  total  length  of  time  from  vine  to  bottle  not  exceeding 
three  days.  Such  juice  will,  however,  develop  a  crystalline  deposit 
of  cream  of  tartar.  This  does  not  affect  the  flavor  and  injures  the 
juice  in  no  way,  except  in  appearance..  The  deposit  is  small,  but 
might  cause  the  consumer  to  doubt  the  purity  of  the  juice  unless  the 
label  were  designed  to  explain  the  presence  and  character  of  the 
crystals. 

This  method  reduces  the  expense  of  manufacture  and  the  invest- 
ment in  equipment.  Juice  so  made  is  handled  fewer  times  than  that 
made  by  the  usual  methods  and  is  therefore  richer  in  flavor  and  of 
better  color.    It  is  a  method  worthy  of  commercial  trial. 


20  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

16.  Carbonating  Juice  before  Bottling. — Carbonated  juices  are 
always  more  popular  than  still  juices  for  the  same  reason  that  sharp 
or  sparkling  cider  is  preferred  to  the  juice  fresh  from  the  apple. 
Besides  increasing  the  palatability  of  the  juice,  the  carbonation  greatly 
reduces  the  temperature  necessary  for  sterilization.  Juices  that  are 
lightly  carbonated  may  be  sterilized  at  150°  F.  or  less. 

A  carbonated  juice  should  be  clear  and  free  from  sediment  to  be 
attractive. 

Carbonating  consists  in  impregnating  the  juice  with  carbonic  acid 
gas  and  in  bottling  under  a  pressure  of  the  same  gas.  Carbon  dioxide, 
that  is,  carbonic  acid  gas,  is  sold  in  the  liquefied  state  in  steel  cylinders. 

The  solubility  of  the  gas  in  the  juice  is  greatly  increased  by  low 
temperatures.  A  convenient  and  effective  system  of  carbonating  con- 
sists in  chilling  the  juice  to  near  freezing  and  in  agitating  the  chilled 
juice  in  a  strong,  sealed  container  into  which  the  gas  is  admitted  under 
pressure.  Fair  results  can  be  obtained  by  carbonizing  the  chilled  juice 
in  open  containers.  Pressure  gauges,  safety  valves,  and  automatic 
pressure  controls  should  be  used  to  avoid  accidents  from  bursting 
pressures.  Fifteen  to  twenty  pounds'  pressure  per  square  inch  will  be 
sufficient.  The  juice  after  carbonation  is  filled  directly  into  bottles 
and  capped  at  once. 

Another  system  of  carbonating  consists  in  impregnating  the  juice 
by  aspiration;  that  is,  the  chilled  juice  is  passed  through  a  column 
into  which  the  carbonic  acid  gas  is  admitted.  The  juice  flows  directly 
into  the  bottles  under  pressure. 

A  convenient  and  simple  method  for  small  scale  operations  is  to 
place  the  juice  in  a  heavy  beer  keg;  to  connect  a  cylinder  of  gas  to  a 
carbonating  inlet  which  may  be  purchased  for  such  barrels;  to  admit 
gas  up  to  fifteen  pounds'  pressure  and  agitate  and  roll  the  barrel  for 
about  fifteen  minutes,  admitting  gas  frequently  to  maintain  the  pres- 
sure at  fifteen  pounds.  If  the  juice  is  cool,  it  may  then  be  drawn 
off  and  bottled,  but  it  will  be  necessary  to  admit  gas  to  the  barrel 
occasionally  during  filling  of  the  bottles  to  maintain  a  constant 
pressure. 

The  bottles  of  carbonated  juice  are  sealed  and  sterilized  at  150°  F. 
for  thirty  minutes.  Do  not  handle  the  bottles  while  they  are  still  hot 
because  they  will  be  under  a  dangerous  pressure  due  to  expansion 
from  heat. 

17.  Canning  Grape  Juice. — The  time  and  expense  of  manufacture 
are  greatly  reduced  if  the  juice  is  canned.  Red  juice  tends  to  become 
blue  or  purple  in  color  after  canning,  unless  heavily  lacquered  cans  are 


Circular  220  unfermented  fruit  juices  21 

used.  For  this  reason  white  juice  has  been  canned  more  satisfactorily 
than  red  juice. 

The  canning  of  white  juice  may  well  become  an  important  line  of 
endeavor  for  fruit  canneries.  A  process  suitable  for  commercial  use 
is  as  follows : 

The  grapes  are  crushed  and  pressed.  The  juice  may  be  heated  to 
170°  F.  and  allowed  to  stand  over  night  to  cool  and  settle,  or  may  be 
passed  at  once  through  cooling  coils  after  heating.  The  cool  juice 
may  be  filtered  roughly  and  filled  into  cans.  A  can  syruping  machine 
would  make  an  excellent  filling  device.  The  filled  cans  may  be  passed 
through  a  cannery  exhaust  box  slowly  and  heated  therein  to  175°  F. 
The  cans  of  hot  juice  may  be  capped  at  once  and  turned  upside  down 
to  cool.  Lacquered  cans  should  be  used.  Red  juice  may  be  canned  in 
a  similar  manner. 

A  modified  process  consists  in  warming  the  filtered  juice  to  about 
140°  F.,  filling  into  cans,  sealing,  and  sterilizing  in  water  at  175°  F. 
for  twenty-five  minutes. 

Another  process  in  use  for  apple  juice  consists  in  heating  the  filtered 
juice  to  175°  F.  and  filling  into  cans  at  this  temperature  and  sealing 
without  further  treatment.  Red  grape  juice  has  been  canned  experi- 
mentally by  heating  the  crushed  grapes  to  160°  F.,  pressing,  filtering, 
and  canning  as  directed  above. 

The  canned  juice  posseses  as  much  flavor  as  the  bottled  product, 
but  will  be  slightly  cloudy.  It  may  be  produced  very  cheaply  and  it 
should  be  possible  to  sell  it  for  30c  or  less  per  quart  can  at  retail  if 
grapes  may  be  had  at  $40  per  ton  or  less.  At  $40  per  ton  for  grapes 
the  raw  material  for  one  quart  of  juice  costs  6*40.  The  can  and  label 
will  cost  about  4c,  the  cost  of  manufacture  not  more  than  2c,  and  the 
case  about  2c  per  quart.  This  gives  a  total  cost  of  about  1414c  per 
quart. 

18.  Pasteurized  Juice  in  Barrels  for  Export. — Either  red  or  white 
juice  may  be  pasteurized  into  sterilized  barrels  as  described  under 
"Bulk  pasteurization"  at  175°  F.  The  barrels  must  be  bunged  at  once 
with  sterilized  bungs  and  the  outside  of  the  barrels  coated  with 
paraffin,  shellac  or  other  impervious  coating  to  prevent  infection.  Such 
juice  may  be  exported  to  foreign  countries  for  various  purposes  or 
sold  in  the  United  States  for  use  in  large  soft  drink  dispensaries  or 
at  picnics,  etc.,  where  a  cheap  juice  of  good  quality  is  desired.  The 
possibilities  of  the  marketing  of  juice  in  this  form  have  been  tested  by 
a  large  company  during  the  past  season. 


22  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

19.  Preservation  of  Juice  with  Sulfurous  Acid. — If  grape  juice  is 
stored  in  a  cool  place  (60°  F.-65°  F.  or  less),  it  may  be  kept  for  at 
least  one  year  by  the  addition  of  one-tenth  of  one  per  cent  of  sulfurous 
acid,  which  corresponds  to  12^2  ounces  of  sulfurous  acid  or  about  134 
gallons  of  commercial  six  per  cent  sulfurous  acid  solution  per  100 
gallons  of  juice.  Juice  stored  at  higher  temperatures  requires  pro- 
portionally larger  amounts  of  the  sulfurous  acid  to  prevent  fermenta- 
tion. 

Juice  preserved  in  this  way  cannot  be  used  for  drinking  purposes 
until  the  sulfurous  acid  is  removed.  This  can  be  done  by  heating  the 
juice  to  160°  F.  and  at  the  same  time  passing  a  violent  stream  of  air 
through  it  for  about  an  hour  and  a  half.  This  removes  enough  of  the 
sulfurous  acid  to  permit  the  juice  to  be  used  for  drinking  purposes, 
syrup  making,  or  vinegar  manufacture;  or  the  juice  after  removal  of 
the  preservative  may  be  sterilized  in  barrels.  J.  H.  Wheeler  of  St. 
Helena  preserved  and  successfully  treated  75,000  gallons  of  juice  in 
this  way  during  the  past  season. 

This  method  of  preservation  makes  it  possible  to  utilize  the  storage 
tanks  of  wineries  to  good  advantage  and  makes  it  possible  for  a  grape 
syrup  factory  to  have  juice  on  hand  throughout  the  year  at  little 
expense. 

Juice  preserved  with  sulfurous  acid  should  not  be  allowed  to  come 
in  contact  with  iron  or  copper;  only  aluminum  or  tin  (preferably 
aluminum)  or  glass  should  be  used.  A  wooden  vat  and  aluminum 
steam  coil  may  be  used  to  heat  the  juice  during  removal  of  the  pre- 
servative ;  or  a  large  glass-lined  steam  jacketed  vat  of  the  type  used 
for  concentrating  tomato  products  is  excellent.  An  air  compressor  of 
rather  large  capacity  is  also  necessary.  This  should  be  connected  to 
an  aluminum  pipe  leading  to  the  bottom  of  the  heating  vessel,  or  a 
piece  of  steam  hose  may  be  used  to  deliver  the  air. 

Red  juice  when  preserved  with  sulfurous  acid  becomes  almost  white 
in  color,  but  when  the  sulfurous  acid  is  removed  by  aeration  practically 
all  of  the  color  returns. 

It  must  be  stated,  however,  that  aeration  does  not  remove  all  of  the 
sulfurous  acid  and  if  such  juice  is  offered  for  sale  it  must  bear  the 
statement  that  it  contains  sulfurous  acid. 

20.  Home  Methods  of  Grape  Juice  Making. — A  red  juice  is  more 
satisfactorily  made  in  the  kitchen  than  a  white  juice.  The  grapes 
should  not  be  too  ripe  but  should  be  still  rather  tart  when  picked.  A 
mixture  of  Muscat  and  some  red  wine  grapes  gives  a  very  pleasing 
juice. 


Circular  220  unfermented  fruit  juices  23 

Crush  the  grapes  in  a  small  household  size  crusher  or  merely  crush 
them  with  the  hands  into  an  agateware,  tin,  or  aluminum  kettle. 

Heat  slowly  with  stirring  to  150°  F. ;  a  dairy  thermometer  is  useful 
for  testing  the  temperature.  Set  aside  for  about  two  hours.  Place  in 
a  jelly  bag  or  in  a  heavy  cloth  in  a  small  press.  Allow  to  drain  into  a 
pan  and  press  the  skins  and  pulp. 

Strain  through  a  cloth  or  felt  bag.  Fill  into  clean  scalded  bottles. 
Cork  bottles  with  corks  that  have  been  boiled  five  minutes  in  water. 
Tie  the  corks  down  with  string.  Crown  finish  bottles,  crown  caps 
and  a  small  hand-power  capping  machine  may  be  used.  See  figure  16, 
illustrating  this  capper.  Place  the  bottles  horizontally  on  a  false 
bottom  in  a  wash  boiler  or  large  kettle.  Fill  the  vessel  with  water  and 
heat  the  water  to  175°  F.  for  thirty  minutes.  Remove  bottles  and 
seal  corks  with  melted  paraffine. 

The  strained  juice  prepared  as  directed  above  may  be  heated  to 
180°  F.  and  poured  into  hot,  scalded  Mason  or  glass  top  jars.  Scalded 
rubbers  and  caps  are  then  put  in  place,  the  jars  sealed  and  turned 
upside  down  to  cool.  This  method  is  simple  and  effective.  Never 
heat  grape  juice  to  the  boiling  point. 

21.  Costs  and  Returns  on  Grape  Juice. — Judging  from  the  results 
of  our  experiments  at  the  University  Farm  it  would  be  possible  to 
erect  a  small  grape  juice  plant  such  as  the  University  possesses  for 
about  $1000,  exclusive  of  barrels,  bottles,  or  other  juice  containers. 
This  plant  will  dispose  of  about  five  tons  of  grapes  per  day  or  about  one 
hundred  tons  in  a  season  of  twenty  days;  or  would  produce  15,000  to 
20,000  gallons  of  juice  per  season.  It  consists  of  a  shed,  a  small  con- 
tinuous pasteurizer  made  of  50  feet  of  five-eighths  inch  aluminum  pipe 
coiled  inside  a  50-gallon  barrel,  a  3  H.P.  boiler  (5  H.P.  is  better),  a 
cement  vat  5  feet  long  by  2y2  feet  wide  by  2  feet  deep  with  steam  coil 
for  pasteurizing  bottled  juice,  a  small  asbestos  Seitz  filter,  a  foot  power 
Crown  bottle  capper,  a  hand  power  grape  crusher,  medium  size  hand 
power  screw  basket  press,  and  miscellaneous  utensils  such  as  fiber  tubs, 
pails,  dippers,  hose,  etc.  To  this  must  be  added  glass  carboys  for 
15,000  gallons  of  juice,  60,000  quart  bottles  or  their  equivalent  in  other 
sizes,  caps,  labels,  and  shipping  boxes.  Our  estimated  cost  is  as 
follows : 

Estimated  Cost  per  Quart  Bottle 

Grapes  at  $40  per  ton  and  yield  of  600  quarts  per  ton $  .0625 

Bottle  at  4y2c 0450 

Caps  at  30c  per  gross  0020 

Labels  at  $10  per  M  0100 

Cost  of  handling  at  16c  per  gallon  0400 

Cost  of  packing  for  shipment  0300 

Total .$  .1895 


24  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Total  cost  per  quart,  about  19c,  allowing  no  charge  for  interest  on 
investment  or  depreciation.  It  should  be  possible  to  sell  grape  juice 
retail  at  40c  per  quart  at  a  good  profit  for  all  concerned.  It  now  sells 
at  75c  to  90c  per  quart  retail. 

Canned  juice,  it  is  believed,  could  be  produced  for  less  than  15c 
per  quart  can  and  retailed  at  30c  or  less  per  quart.  Apple  juice  has 
retailed  at  15c  per  quart  in  cans. 

UNFERMENTED  APPLE  JUICE 

The  manufacture  of  apple  juice  has  become  an  important  industry 
in  the  Pacific  Northwest,  where  several  breweries  have  been  successful 
in  producing  a  high  class  un fermented  cider.  Several  very  successful 
factories  of  moderate  size  exist  in  California. 

Carbonated  cider  is  most  in  demand  and  must  be  brilliantly  clear. 

The  general  principles  are  similar  to  those  used  in  making  grape 
juice.  Apple  juice  is  more  easily  injured  in  flavor  by  heat  than  is 
grape  juice,  and  therefore  requires  greater  care. 

1.  Varieties  of  Apples. — Apples  of  sprightly  to  acid  flavor  are  best 
provided  they  are  ripe  and  possess  a  full  apple  flavor.  Of  the  com- 
mercially grown  varieties  of  California,  the  Yellow  Newtown  has  been 
found  satisfactory.  The  Bellflower  is  of  poor  flavor.  The  Gravenstein 
is  of  fair  quality  for  juice  but  not  so  good  as  the  Newtown.  Northern 
Spy,  AVinesap,  and  other  varieties  of  sprightly  flavor  are  excellent, 
but  scarce.  Varieties  of  very  low  acid,  such  as  the  Tolman  Sweet,  are  of 
little  value  and  produce  juices  which  are  difficult  to  sterilize.  Varieties 
also  which  may  have  sufficient  acid  but  which  are  of  poor  flavor  are 
not  successful.  To  this  class  would  belong  the  Bellflower  and  Ben 
Davis. 

The  apples  should  be  mature  enough  to  possess  their  full  flavor,  but 
should  not  be  over-ripe,  because  of  the  decrease  in  acidity  after 
maturity  is  reached  and  because  juice  from  over-ripe  fruit  is 
"gummy"  and  very  difficult  to  filter. 

Only  clean  sound  fruit  should  be  used.  This  usually  means  that 
the  fruit  should  be  carefully  sorted  and  washed  before  crushing.  See 
illustration  of  fruit  washer  (figure  1). 

2.  Crushing  and  Pressing. — Apple  tissue  is  firm  and  tough  and 
the  cells  possess  heavy  walls.  Consequently  crushing  must  be  thorough 
and  pressing  severe  to  obtain  a  high  yield  of  juice.  Crushing  too 
finely,  however,  causes  the  pulp  to  be  too  soft  to  press  without  danger 
of  breaking  the  press  cloths.     Pieces  one-fourth  to  one-half  inch  and 


Circular  220 


UNFERMENTED    FRUIT    JUICES 


25 


one-eighth    to    one-fourth    inch    in    diameter    are    satisfactory.      The 
crusher  can  be  set  to  grind  to  any  desired  degree  of  fineness. 

The  crushed  fruit  is  placed  in  heavy  coarse-weave  cloths  and  the 
fruit  is  enclosed  by  folding  the  cloth.  Each  cloth  of  fruit  is  placed 
between  racks  made  of  hardwood  slats.  Pressure  is  applied  usually 
by  a  hydraulic  pump.  A  pressure  of  at  least  500  pounds  per  square 
inch  is  necessary  for  the  best  results.  A  ton  of  apples  should  yield 
160  gallons  of  juice  if  well  pressed.  The  pomace,  that  is,  the  press 
cake,  will  yield  more  juice  if  broken  and  pressed  a  second  time,  but 
probably  may  best  be  used  for  by-products,  especially  vinegar. 

3.  Clearing  the  Juice. — A  common 
method  of  clearing  the  juice  consists  in 
heating  to  precipitate  proteins  and  gums, 
cooling  the  heated  juice  and  filtering  until 
clear.  Methods  of  filtering  described  for 
grape  juice  can  be  used  for  apple  juice. 
Two  or  more  filtrations  are  usually  neces- 
sary. If  the  juice  is  to  be  carbonated  before 
bottling  it  needs  to  be  heated  to  150°  F.  to 
155°  F.  only;  but  if  to  be  bottled  without 
carbonating  it  must  be  heated  to  165°  F.  to 
170°  F.  In  other  words,  the  juice  is  heated 
before  filtration  to  a  temperature  equal  to 
or  greater  than  that  to  be  used  in  sterilizing 
the  juice  in  the  final  bottles,  because  if  it  is 
heated  to  a  lower  temperature  before  filtra- 
tion the  higher  temperature  during  final 
pasteurizing  may  cause  the  juice  to  become 
cloudy  through  further  precipitation  of 
protein.  This  principle  is  very  important 
and  holds  for  other  fruits.  Some  factories  filter  the  fresh  unpasteur- 
ized unheated  juice  and  bottle  without  the  preliminary  pasteurizing 
noted  above. 

Aluminum,  tin,  glass,  silver  and  monel  metal  surfaces  may  be  used 
in  contact  with  hot  apple  juice  with  safety.  Most  other  metals  are 
acted  upon  by  the  acid  of  the  juice. 

4.  Carbonating  Apple  Juice. — The  methods  described  for  carbonat- 
ing grape  juice  are  also  suitable  for  apple  juice. 

If  carried  out  at  room  temperature  the  juice  should  be  carbonated 
to  about  15  pounds'  pressure.  If  the  juice  is  first  chilled  to  about  33°  F. 
to  36°  F.  it  will  absorb  the  gas  more  readily  and  carbonating  to  5 


Fig.  13.    Wood  pulp  fruit 

juice  filter. 
(Courtesy  of  Karl  Kieffer 

Company) 


26  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT   STATION 

pounds'  pressure  in  a  clean  barrel  will  be  sufficient;  or  merely  passing 
the  gas  through  the  cold  juice  will  cause  it  to  absorb  enough  to  impart 
a  sharp  flavor  to  the  bottled  juice,  but  this  method  is  wasteful  of  gas. 
Apple  juice  is  greatly  improved  by  carbonating  and  all  such  juice 
for  sale  in  bottles  should  be  so  treated. 

5.  Sterilizing. — Carbonated  juice  may  be  sterilized  at  150°  F.  for 
thirty  minutes.  If  the  juice  has  not  been  carbonated  it  should  be 
heated  to  170°  F.  for  thirty  minutes.  Carbonating  reduces  the  tem- 
perature of  sterilization  because  it  checks  the  development  of  mold. 

6.  Spoiling  of  Apple  Juice  by  Mold. — Bottle  caps  are  the  usual 
source  of  infection.  Caps  are  readily  sterilized  before  use  by  immers- 
ing them  in  boiling  water  for  one  minute.  This 
sterilization  will  greatly  reduce  loss  of  juice 
from  mold  growth.  Bottles  should  also  be 
sterilized  in  steam  or  hot  water  before  use  to 
further  reduce  danger  of  mold  infection. 

7.  Vanned  Apple  Juice. — Apple  juice  re- 
tains its  flavor  well  in  cans  and  this  method 
offers  the  cheapest  way  of  placing  the  juice  on 
the  market  in  small  containers  in  sterilized 
form. 

Fig.  14.    Bottling  mXiine         Canned  juice  need  not  be  perfectly  clear, 
for  fruit  juices.  but  should  not  show  a  heavy  deposit  in  the  can. 

(Courtesy  of  U.S.  Bottlers'  rm      e  in  ,,      -t  i  i 

Machinery  Company)  rhe  following  method  has  proved  very  suc- 

cessful in  our  investigational  work  : 
The  fruit  is  crushed  and  pressed.  The  juice  is  then  filtered  through 
felt  filter  bags  or  heavy  duck  bags  to  remove  particles  of  pulp.  It  is 
then  heated  to  150°  F.  and  transferred  while  still  hot  to  enamel-lined 
sanitary  open-top  cans  and  sealed.  The  cans  should  be  filled  com- 
pletely in  order  that  as  little  air  as  possible  shall  be  left  in  the  can; 
air  space  in  the  sealed  can  causes  rapid  corrosion  of  the  tin.  The 
sealed  cans  are  placed  in  a  tank  of  water  which  is  heated  to  170°  F. 
for  thirty  minutes. 

Another  method  in  use  on  a  commercial  scale  is  the  following: 
The  fresh  juice  from  the  press  is  strained  through  several  layers  of 
cheese  cloth ;  is  then  heated  to  180°  F.  and  run  directly  into  cans 
which  are  filled  level  full.  The  cans  are  sealed  immediately  and  no 
further  heating  is  given.  Usually  such  juice  is  not  so  clear  as  that 
made  by  the  first  process  but  is  of  good  flavor. 


Circular  220  unfermentkd  FRUIT  JUICES  27 

LOGANBERRY  JUICE 

Loganberry  juice  has  become  very  popular  during  the  past  few 
years  and  is  now  produced  upon  a  large  industrial  scale  in  Oregon, 
making  the  growing  of  this  fruit  very  profitable.  The  development 
of  loganberry  juice  manufacture  is  largely  due  to  the  work  of  Pro- 
fessor C.  I.  Lewis,  formerly  of  the  Oregon  Agricultural  College.  The 
juice  is  of  deep  red  color,  very  rich  flavor,  and  high  acidity. 
Thoroughly  ripe  fruit  gives  the  best  juice ;  that  from  under-ripe  berries 
being  light  in  color,  excessively  tart,  and  astringent  in  flavor. 

1.  Extraction  of  Juice. — The  juice  is  best  extracted  by  a  combina- 
tion of  crushing,  heating,  and  pressing. 

The  berries  may  be  crushed  in  a  grape  crusher,  but  wooden  or 
tinned  rollers  should  be  used  because  the  acid  of  the  juice  attacks  iron. 
The  crushed  fruit  should  be  heated  in  tin-lined  or  glass-lined  kettles, 
with  constant  stirring,  to  about  170°  F.  and  pressed  at  once.  Aluminum 
is  rapidly  attacked  by  this  juice.  Long  continued  heating  extracts 
tannin  and  disagreeable  flavors  from  the  seeds.  The  rack  and  cloth 
type  of  apple  press  should  be  used  for  pressing. 

2.  (Hearing  the  Juice. — The  juice  should  be  cooled  after  pressing 
and  before  filtration.  Because  the  juice  is  rich  in  pectins  and  gums  it 
is  difficult  to  filter.  Several  filtration^  through  wood  pulp  or  asbestos 
are  usually  necessary  to  render  the  juice  bright.  Filtration  is  assisted 
by  the  addition  of  " Filter- C el."  The  flavor  of  the  filtrate,  however, 
is  slightly  impaired  by  use  of  too  large  amounts  of  this  material. 

Clarification  may  also  be  accomplished  as  described  for  grape  juice ; 
that  is,  by  sterilizing  the  juice  into  glass  carboys,  allowing  it  to  settle 
several  weeks,  drawing  off  frcm  the  sediment,  and  filtering  or  clearing 
by  Spanish  clay. 

3.  Preparing  Filtered  Juice  for  Bottling. — The  filtered  juice  is 
bottled  in  three  forms:  (1)  natural  juice  undiluted  and  unsweetened, 
(2)  diluted,  sweetened,  and  (3)  sweetened  but  undiluted.  The 
sweetened  undiluted  juice  is  the  best.  Sugar  helps  to  retain  the  fresh 
berry  flavor  and  prevents  the  development  of  a  bitter,  astringent 
flavor  noticeable  in  unsweetened  juices  after  several  months'  storage. 
The  amount  of  sugar  added  is  enough  to  increase  the  Balling  degree 
of  the  juice  to  about  45  per  cent,  which  is  approximately  3%  pounds 
of  sugar  per  gallon  of  juice.  Sweetened  loganberry  juice  is  diluted 
with  about  two  volumes  of  water  (preferably  carbonated)  when  served. 


28  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

4.  Bottling  and  Sterilizing. — The  bottles  are  filled  with  the  cold 
juice  and  capped  with  caps  sterilized  one  minute  in  boiling  water. 
The  juice  may  be  sterilized  by  heating  in  water  to  170°  F.  for  thirty 
minutes.  Carbonating  before  bottling  reduces  the  temperature  of 
sterilizing  and  improves  the  quality  of  the  juice. 

Breweries  have  been  very  successful  in  converting  their  plants 
into  loganberry  juice  factories. 

The  process  of  manufacture  is  very  simple ;  little  equipment  is 
needed  and  the  quality  of  the  product  is  high.  Its  manufacture  should 
therefore  prove  a  profitable  undertaking  for  the  grower  or  growers' 
organizations. 

POMEGRANATE  JUICE 

When  properly  made,  pomegranate  juice  is  a  brilliant  purplish  red 
in  color  and  perfectly  clear;  its  flavor  is  pleasing  and  it  blends  well 
with  other  fruit  juices,  besides  making  a  very  pleasant  beverage  of 
itself  when  diluted  and  sweetened.  Ordinarily  it  will  be  too  tart  in 
flavor  and  the  flavor  is  not  retained  very  satisfactorily  unless  the  juice 
is  sweetened  before  bottling. 

1.  Extraction  of  Juice. — The  "rag"  and  peel  of  the  pomegranate 
contains  so  much  tannin  that  juice  from  these  portions  of  the  fruit  is  so 
"puckery"  that  it  is  undrinkable.  The  desirable  juice  is  in  the  arals 
or  "kernels.'  The  problem  is  to  separate  these  from  the  peel  and 
"rag." 

In  our  laboratory  experiments  the  kernels  were  readily  separated 
from  the  rest  of  the  fruit  by  passing  the  fruit  through  a  modified 
tomato  pulper.  The  outfit  used  consisted  of  a  horizontal  cylinder  about 
three  feet  long  and  twenty  inches  in  diameter.  The  bottom  half  of 
this  cylinder  consisted  of  a  metal  screen  with  three-eighths  inch  open- 
ings; the  upper  half  of  this  cylinder  was  of  wood.  Two  wooden 
paddles  were  attached  to  a  shaft  passing  through  the  cylinder  length- 
wise. The  shaft  was  revolved  at  about  400  R.P.M.  by  means  of  a 
1  H.P.  motor.  The  pomegranates  were  fed  in  at  one  end  of  the 
cylinder.  The  rapidly  revolving  paddles  shattered  the  fruit  by  impact 
and  the  kernels  freed  thereby  fell  through  the  screen  into  a  receptacle. 
The  rag  and  peel  were  thrown  out  through  a  hole  in  the  opposite  end 
of  the  cylinder.  It  was  soon  found  that  iron  could  not  be  used  in 
contact  with  the  fruit  or  juice.  Tin,  aluminum,  Monel  metal,  or  silver 
may  be  used.  Iron  causes  the  juice  to  turn  black  in  color  and  destroys 
the  flavor. 


Circular  220 


UNFERMENTED    FRUIT    JUICES 


29 


The  kernels  obtained  as  noted  above  were  crushed  lightly  in  a  tin- 
lined  crusher  and  were  pressed  between  racks  and  cloths  in  a  hydraulic 
cider  press.  Yields  of  about  ninety  to  one  hundred  gallons  per  ton 
were  obtained. 

2.  Clearing  the  Juice. — It  was  found  that  the  juice  could  be  easily 
clarified  by  heating,  settling,  and  filtration.  The  freshly  pressed  juice 
was  heated  to  165°  F.  and  allowed  to  cool  and  settle  for  twenty-four 
hours.  The  settled  juice  was  racked  from  the  sediment  and  was  found 
to  filter  very  quickly.  Probably  the  high  tannin  content  of  the  juice 
favors  this  natural  clarification. 


Fig.  15.    Simple  device  for  carbonating  fruit  juices  for  small  scale  production. 

3.  Addition  of  Sugar  and  Sterilizing. — If  the  juice  is  very  tart, 
sugar  should  be  added  to  increase  the  Balling  degree  to  about  35° 
to  40°  Balling.  If  the  fruit  is  very  ripe,  sugar  addition  to  increase 
the  juice  to  30°  Balling  will  be  sufficient.  By  tests  made  upon  meas- 
ured samples  the  proper  amount  of  sugar  can  be  quickly  determined. 

Sweet  red  grape  juice  from  thoroughly  ripe  red  wine  grapes  and 
made  as  described  under  "Grape  Juice"  in  this  publication  may  be 
added  to  pomegranate  juice  with  pleasing  results.  The  blend  is  less 
harsh  than  the  straight  pomegranate  juice  and  has  much  more  char- 
acter than  plain  red  juice  from  wine  grapes.  Dr.  E.  M.  Chace  of  the 
United  States  Department  of  Agriculture  Citrus  By-products  Labor- 


30 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


atory  of  Los  Angeles  has  made  a  number  of  pleasing  combinations  of 
pomegranate  juice  with  other  juices,  especially  grape  fruit  juice. 

Bottling,  capping,  and  sterilizing  at  165°  F.  for  thirty  minutes  are 
carried  out  as  described  for  grape  juice. 

CITRUS  FRUIT  JUICES 

1.  Orange  Juice. — No  satisfactory  orange  juice  other  than  that  sold 
fresh  from  the  fruit  has  yet  appeared  upon  the  market.  Many  com- 
panies have  failed  in  attempts  to  produce  orange  juice  upon  a  corn- 


Fig.  16.    Small  hand  power  bottle  capper. 

mercial  scale.  Such  products  as  "orangeade,"  etc.,  are  not  orange 
juice  but  are  preparations  usually  made  up  of  citric  acid,  orange  oil, 
sugar,  and  artificial  coloring  matter,  with  in  some  cases  a  very  small 
amount  of  orange  juice  added. 

Orange  juice  does  not  retain  its  fresh  flavor  in  the  bottle,  but  tends 
in  several  weeks'  time  to  develop  a  "stale"  and  disagreeable  taste. 
On  this  account  no  one  is  advised  to  attempt  to  produce  a  "straight" 
orange  juice  commercially  until  processes  superior  to  those  already 
known  are  discovered.  Small  amounts  for  home  use  may  be  put  up 
if  desired.  In  this  case,  cut  the  oranges  in  half,  extract  the  juice 
on  glass  orange  juice  cones  to  avoid  getting  oil  from  the  skins  into  the 
juice;  or  the  fruit  may  be  peeled,  crushed,  and  pressed.  Leave  the 
yellow  pulp  in  the  juice  because  it  adds  flavor.    Bottle  and  pasteurize 


Circular  220 


UNFERMENTED    FRUIT    JUICES 


31 


thirty  minutes  at  165°  F.     Such  juice  will  be  drinkable,  but  not  of 
high  enough  quality  for  large  scale  production. 

2.  Orange-Lemon  Juice. — Sugar  greatly  decreases  the  tendency  for 
orange  juice  to  become  ''stale."  We  have  made  repeatedly  a  juice 
made  up  of  a  mixture  of  orange  juice,  lemon  juice  and  sugar,  and 
found  this  product  very  palatable  even  after  one  year's  storage. 

The  fruit  was  peeled  in  a  small  vegetable  grating  or  peeling 
machine.  It  was  then  washed  to  remove  adhering  oil  and  was  crushed 
and  pressed  in  an  apple  press.  The  juices 
were  mixed  in  the  proportion  of  one  part 
lemon  juice  to  four  parts  of  orange  juice 
and  sugar  was  added  to  increase  the  Balling 
degree  to  40°  ;  about  six  pounds  of  sugar 
per  gallon  of  juice.  The  fresh,  cloudy,  un- 
filtered  juices  were  found  much  superior  in 
flavor  to  the  clarified  or  filtered  juices.  The 
sweetened  juice  was  bottled  and  pasteurized 
at  165°  F.  for  thirty  minutes.  When  it  is 
to  be  served  it  is  diluted  with  about  twice 
its  volume  of  water,  carbonated  water  pre- 
ferred. 

It  is  believed  that  this  product  possesses 
sufficient  merit  for  commercial  purposes. 

3.  Lemon  Juice. — This  juice  is  produced 
in  several  factories  in  California.  Like 
orange  juice  it  also  develops  a  "stale" 
flavor  after  bottling,  but  is  still  suitable  for 
many  purposes.  The  oil  from  the  skins 
should  be  excluded  from  the  juice,  either 
by  peeling  the  fruit  before  pressing  or  by 
extracting  the  juice  by  means  of  rapidly 
revolving  aluminum  or  bronze  cones  against 
which  the  halved  fruit  is  held.    It  should  be 

strained  through  cloth  to  remove  gross  sediment,  bottled,  and  pasteur- 
ized at  165°  F.  for  thirty  minutes. 

4.  Grape  Fruit  Juices. — This  juice  is  produced  in  Florida  success- 
fully. The  juice  should  be  extracted  in  such  a  way  that  the  oil  from 
the  skins  is  excluded  and  an  excess  of  bitterness  from  the  white  rag 
portion  of  the  skin  avoided.  This  can  be  done  by  cutting  the  fruit  in 
half  and  extracting  the  juice  on  suitably  constructed  revolving  cones. 
(The  name  of  the  manufacturer  of  the  revolving  cones  will  be  sent  by 
the  writer  on  request.) 


Fig.  17.  Foot  power  bottle 
capping  machine  suitable  for 
small  factories. 


32 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Grape  fruit  juice  darkens  in  the  bottle  unless  air  is  excluded.  This 
can  best  be  done,  as  United  States  Department  of  Agriculture  investi- 
gators have  found,  by  heating  the  juice  to  165°  F.  to  170°  F.  in  an 
open  aluminum  vessel  and  filling  the  bottles  immediately  with  the  hot 
juice.  The  bottles  are  filled  to  overflowing  and  capped  at  once.  Thus 
all  air  is  excluded.  The  bottled  juice  is  placed  in  water  at  165°  F. 
and  held  there  for  thirty  minutes  to  sterilize. 


Fig.  18.  Home  made  fruit  juice  press.  Also  suitable  for  pressing  olives  for 
oil.  A,  heavy  wagon  or  automobile  jack;  B,  light  steel  cable  or  one-inch  rope; 
C,  two  pieces  2"x24"x24";  D,  tin-lined  sheet  metal  pan,  30"  x  30"  x  3"  with 
juice  spout  as  shown,  or  wooden  trough  of  same  dimensions;  E,  heavy  burlap  to 
hold  fruit;  F,  three  inch  or  two  inch  floor;  G,  frame  of  2"  X  6"  pine. 


Ten  per  cent  to  fifteen  per  cent  of  sugar  (%  to  l1/^  pounds  of  sugar 
per  gallon)  added  to  the  juice  before  bottling  improves  its  flavor.  The 
juice  is  popular  asa"  before  breakfast ' '  appetizer  and  would  seem  to 
have  considerable  commercial  possibilities. 


